Method of treating osteoporosis with extract of Dioscorea sp

ABSTRACT

A method for treating osteoporosis in a subject in need of such treatment includes administering orally to the subject an effective amount of an extract product of a  Dioscorea  species capable of promoting proliferation and differentiation of bone marrow cells in the subject. Particularly, the  Dioscorea  species is  Dioscorea alata  L. cv. Phyto, characterized by a randomly amplified polymorphic DNA (RAPD) fingerprint including 14 DNA bands ranging from 428 bp, 452 bp, 537 bp, 602 bp, 723 bp, 817 bp, 934 bp, 1140 bp, 1242 bp, 1478 bp, 1641 bp, 1904 bp, 2151 bp and 2918 bp, respectively, when genomic DNA of the  Dioscorea  species is amplified with a primer of SEQ ID NO:9, and the extract product is prepared by a process including: (a) extracting a tuber of the  Dioscorea  species using an alcohol-based solvent in the presence of acetic acid; (b) subjecting the resultant product obtained in (a) to a separating treatment to obtain a soluble fraction; and (c) removing solvent from the soluble fraction obtained in (b) to extract fractions of  Dioscorea  sp.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a divisional of application Ser. No. 11/274,775, filed on Nov. 15, 2005, which is a continuation-in-part of application Ser. No. 10/335,278, filed on Dec. 31, 2002, now abandoned. Each of the prior applications is hereby incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

Dioscorea, also known as “wild yam,” is a member of the monocotyledonous family Dioscoreaceae, which is distributed in the tropical and subtropical regions. There are about 650 species in the world, of which 93 species and 9 varieties are found in China, and 14 species and 5 varieties are found in Taiwan.

Dioscorea is one of the very important pharmaceutical plants used in traditional Chinese medicine, and the medicinal effects thereof have been studied for years. In 1936, Tsukamoto et al isolated diosgenin, a steroid saponin of Dioscorea, from Dioscoreacea family of plants and then use it as raw material for rapid synthesis of medicinal steroids. In a study by Aradhana, M., Rao A. C., Kale R. K. (Indian Journal of Experimental Biology 30:367-370, 1992), it was indicated that diosgenin promotes the growth of epithelial cells of rat mammary glands. In Biochemical & Biophysical Research Communications 207(l):398-404, February 1995, Beneytout, J. L. et al. reported that diosgenin induces morphological and biochemical changes in characteristic of megakaryocyte cells when diosgenin is added to human erythroleukemia (HEL) cell cultures and, thus, diosgenin can be used as a megakaryotic differentiation inducer of HEL cells. In Araghiniknam, M., et al., Life Sciences 59(11):147-157, 1996, a steroid extract of Dioscorea was indicated to possess significant activities as an anti-oxidant to modify serum lipid levels.

Dehydroepiandrosterone (DHEA) has a similar chemical structure to diosgenin, and is known to have anti-cancer, anti-oxidation, and anti-diabetic effects, as well as an effect on the regulation of bone mass. The serum levels of DHEA gradually decrease as age increases, and are related to aging. It was speculated from various studies that the diosgenin extract of Dioscorea might be converted into DHEA in the human body and thus supplements the DHEA which decreases with aging. However, these studies were only conducted on old people taking diosgenin present in the Dioscorea to investigate if diosgenin could reduce the over-oxidation of serum lipids, lower the triglycerides in blood serum and increase high density level (HDL) of cholesterol while decreasing the over-oxidation damage of low density level (LDL) of cholesterol.

Concerning the effect of DHEA on regulation of bone mass, in Life Sciences 62(1):59-68, 1998, Scheven, B. A. A., et al reported that DHEA and its sulfate derivative (DHEA-S) failed on their own to exert direct, independent, significant effects on the growth and differentiation of human osteoblastic cells, but treating the cells in conjunction with a bone cell modulating agent, 1,25(OH)₂D₃, resulted in enhancement of specific alkaline phosphatase (ALP) activity, which is the specific maker of maturing osteoblastic cells. This study shows that the effects of DHEA and DHEA-S on osteoblastic cell growth and differentiation are likely to be mediated via an effect on 1,25(OH)₂D₃-induced change in bone cells.

In accordance with the present invention, it was found that the extract of a particular Dioscorea species, Dioscorea alata L. cv. Phyto, which has been given the scientific name “Dioscorea alata (No. YMM-PH3)” by the Research Center for Drug Discovery at the National Yang Ming University, Taipei, Taiwan, R.O.C., (referred to hereinafter as “Dioscorea alata L. cv. Phyto”) and the further extracted fractions possess biological activity on cell regeneration. Specifically, it was found that the extract of the Dioscorea sp. and the further extracted fractions per se, without the presence of any bone cell modulating agent, can stimulate the proliferation and differentiation of the osteoprogenitor cells so as to supplement the osteoprogenitor cells in the bone and promote maturity of osteoblastic cells and mineralization of osteoblastic cells, thereby achieving bone repair, restoration and reproduction and in turn preventing and treating osteoporosis. Moreover, the extract of the Dioscorea sp. not only stimulates the proliferation and differentiation of hematopoietic stem cells in bone marrow in the presence of granulocyte-macrophage colony-stimulating factor (GM-CSF), but also facilitates recovery of patients suffering from the deficiency of leukocytes and erythrocytes caused by anti-cancer drug treatment, and thus, can be used in combination with an anti-cancer drug as a chemotherapeutic adjuvant.

BRIEF SUMMARY OF THE INVENTION

The present invention provides a method for treating osteoporosis in a subject in need of such treatment, comprising administering orally to the subject an effective amount of an extract product of a Dioscorea species capable of promoting proliferation and differentiation of bone marrow cells in the subject, wherein the extract is prepared by a process comprising: (a) extracting a tuber of the Dioscorea species using an alcohol-based solvent in the presence of acetic acid; (b) subjecting the resultant product obtained in (a) to a separating treatment to obtain a soluble fraction; and (c) removing solvent from the soluble fraction obtained in (b). The preferred Dioscorea species is Dioscorea alata L. cv. Phyto, characterized by a randomly amplified polymorphic DNA (RAPD) fingerprint comprising 14 DNA bands ranging from 428 bp, 452 bp, 537 bp, 602 bp, 723 bp, 817 bp, 934 bp, 1140 bp, 1242 bp, 1478 bp, 1641 bp, 1904 bp, 2151 bp and 2918 bp, respectively, when genomic DNA of the Dioscorea species is amplified with a primer of SEQ ID NO:9.

The present invention also provides an extract product of a Dioscorea species as described above, wherein the extract product is prepared by a process comprising: (a) extracting a tuber of the Dioscorea species using an alcohol-based solvent in the presence of acetic acid; (b) subjecting the resultant product obtained in (a) to a separating treatment to obtain a soluble fraction; and (c) removing solvent from the soluble fraction obtained in (b). The extract is preferably from Dioscorea alata L. cv. Phyto, characterized by a RAPD fingerprint comprising at least 14 DNA bands ranging from 428 bp, 452 bp, 537 bp, 602 bp, 723 bp, 817 bp, 934 bp, 1140 bp, 1242 bp, 1478 bp, 1641 bp, 1904 bp, 2151 bp and 2918 bp, respectively, when the genomic DNA of the Dioscorea alata L. cv. Phyto is amplified with a primer of SEQ ID NO:9.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The foregoing summary, as well as the following detailed description of the invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there are shown in the drawings embodiments which are presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown.

In the Drawings:

FIG. 1 show bar graphs identified as FIGS. 1A and 1B. FIG. 1A illustrates the effects of the extract of Dioscorea sp. (DioMs) and DHEA and FIG. 1B illustrates the effects of each further extracted portion (DioMPw, DioMPb and DioMPe) on the proliferation of osteoprogenitor cells of C3H mice;

FIG. 2 includes bar graphs identified as FIGS. 2A and 2B. FIG. 2A shows the effects of the extract of Dioscorea sp. and FIG. 2B illustrates the effects of each further extracted fraction on the differentiation of osteoprogenitor cells into matured osteoblastic cells of mice in vitro determined by alkaline phosphatase (ALP) activity;

FIG. 3 is a bar graph showing the in vitro effects of the extract of Dioscorea sp. on alkaline phosphatase (ALP) activity of the bone marrow cells derived from a patient suffering from glucocorticoid-induced osteoporosis;

FIG. 4 includes bar graphs identified as FIGS. 4A and 4B. FIG. 4A shows the in vivo effects of the extract of Dioscorea sp. on the differentiation of osteoprogenitor cells into matured osteoblastic cells of mice determined by alkaline phosphatase (ALP) activity, FIG. 4B shows the effects of the extract on the mineralization of the bone mass in the bone marrow cells of the healthy mice determined by the nodule formation;

FIG. 5 includes bar graphs identified as FIGS. 5A and 5B. FIG. 5A shows the in vivo effects of the extract of Dioscorea sp. on alkaline phosphatase (ALP) activity, and FIG. 5B shows the effects of the extract on the mineralization of the bone mass in the bone marrow cells of ovariectomized mice;

FIG. 6 shows the RT-PCR result of cytokines in bone marrow cells isolated from mice which are orally administered the extract of Dioscorea sp. according to the present invention;

FIG. 7 consists of FIGS. 7A-7E, which are phase contrast micrograph images showing the effect of the extract of Dioscorea sp. on morphological changes of the primary cultured mouse bone marrow cells in the presence of epithelial growth factor (EGF);

FIG. 8 is a graph that shows the in vivo effect of the extract of Dioscorea sp. on the leukocyte count in the peripheral blood of leucopenia mice induced by cyclophophamide (CY);

FIG. 9 is a bar graph showing the in vivo effect of the extract of Dioscorea sp. on red blood cell (RBC) count in the peripheral blood of cyclophosphamide (CP)-induced leukopenic mice suffering from severe anemia;

FIG. 10 is a bar graph showing the in vivo effect of the extract of Dioscorea sp. on hemoglobin content in the peripheral blood of cyclophosphamide (CP)-induced leukopenic mice suffering from severe anemia;

FIG. 11 is a composite photographic image showing electrophoretic marker profiles of amplification products for a test panel of 14 Dioscorea species amplified with a single randomly amplified polymorphic DNA (RAPD) primer of SEQ ID NO:9; and

FIG. 12 is a dendrogram illustrating a phylogenetic tree of 14 Dioscorea species based on their genetic similarity determined by RAPD analysis.

DETAILED DESCRIPTION OF THE INVENTION

As used herein the following terms may be used for better interpretation of claims and specification.

The term “primer” refers to a nucleic acid fragment or sequence that is complementary to at least one section along a strand of the sample nucleic acid, wherein the purpose of the primer is to sponsor and direct nucleic acid replication of a portion of the sample nucleic acid along that string. In RAPD amplification, single arbitrary primers are used to amplify non-targeted segments of nucleic acid which are located between the primer sequence sites in opposing DNA strands.

A “test panel” is herein defined as a particular group of organisms of individuals selected on the basis of their genetic similarity to each other, or their genetic dissimilarity to another group (i.e., another genus, species, subspecies).

The term “RAPD” refers to “random amplified polymorphic DNA”. “RAPD amplification” refers to a method of single primer directed amplification of nucleic acids using short primers of arbitrary sequence to amplified non-targeted, random segments of nucleic acid as disclosed in U.S. Pat. No. 5,126,239, the disclosure of which is hereby incorporated by reference. “RAPD method” or “RAPD analysis” refers to a method for the detection of genetic polymorphisms involving the non-targeted amplification of nucleic acids using short primers of arbitrary sequence, whereby the profile or fingerprint of “RAPD” amplification products is compared between samples to detect polymorphisms. “RAPD primers” refers to primers of about 8 bp to about 13 bp, of arbitrary sequence, useful in the RAPD amplification or RAPD analysis according to the instant method.

According to the present invention, the Dioscorea species from which the extract product is made is characterized by a randomly amplified polymorphic DNA (RAPD) fingerprint with a random primer, such as primer OPA-18 having an oligonucleotide sequence of AGGTGACCGT (SEQ ID NO:9). The RAPD fingerprint is generated by a RAPD analysis, which involves amplifying genomic DNA of a plurality of Dioscorea species in the test panel with the OPA-18 primer. As the genomic DNA is amplified by polymerase chain reaction (PCR), a set of discontinuous DNA fragments are obtained for each Dioscorea species and expressed as DNA bands of different molecular sizes on an electrophoretic gel. As explained in Example 10 below, and as shown in FIG. 11, there are 14 DNA bands ranging from 428 bp, 452 bp, 537 bp, 602 bp, 723 bp, 817 bp, 934 bp, 1140 bp, 1242 bp, 1478 bp, 1641 bp, 1904 bp, 2151 bp and 2918 bp, respectively, when the genomic DNA is amplified with the OPA-18 primer of SEQ ID NO:9.

Next, a similarity index, that is defined as a ratio of total RAPD bands shared between two species in a cluster analysis, is determined. The similarity index is determined based on the following equation: F2n _(xy) /n _(x) +n _(y) wherein n_(xy) is the number of common DNA bands in Dioscorea species x and y, and n_(x) and n_(y) are the total DNA bands in Dioscorea species x and y respectively. Based on the RAPD fingerprint results and a comparison with other known species of Dioscorea (see FIG. 12), it is believed that the Dioscorea species (or sub-species) used in the invention is different from the known species of Dioscorea, and thus is new.

The present invention is based on the discovery of the biological activities of the extract of the new Dioscorea species as characterized in the invention, in particular the activity on cell regeneration. It was confirmed by the experiments that the extract and the further extracted fractions of the Dioscorea sp. prepared in accordance with the method of this invention include active substances that enhance the proliferation and differentiation of mouse bone marrow progenitor cells. Specifically, the extract and the further extracted fractions of the Dioscorea sp. per se enhance cell proliferation of functional osteoprogenitor cells and even extensively induce the differentiation of osteoprogenitor cells into osteoblastic cells and enhance the mineralization of osteoblastic cells. Moreover, the extract of the Dioscorea sp. can alleviate the side-effects caused by an anti-cancer drug. Specifically, the extract restores the leukocytes and erythrocytes present in the peripheral blood of the mice treated with cyclophosphamide (CY). Therefore, the extract of the Dioscorea sp. would be useful in the prevention and treatment of osteoporosis, a common disease in the aging process, and may be used in combination with an anti-cancer drug as a chemotherapeutic adjuvant.

Stem cells are cells capable of self-renewal and differentiation. Stem cells are present at the maximal level during the embryonic period, and gradually decrease in number with aging. Thus, it was speculated that there is an important correlation or association between stem cells and aging. The stem cells in adults can generate a specific response toward a specific message transmitted through a microenvironment change generating new stem cells or differentiating into specific cells. When the stem cells receive a differentiation message, the stem cells rapidly reproduce in large amounts, and then finally proceed to differentiation. These stem cells are used for maintaining the balance of cells in adults, and replenish the number of cells that die due to natural causes or injuries.

The stem cells in bone marrow are divided into two types, the hematopoietic stem cells, which produce two more specialized types of stem cells, lymphoid progenitor cells (which give rise to T and B lymphocytes) and myeloid progenitor cells (which give rise to leukocytes, erythrocytes, and megakaryocytes), and stromal cells, which are the source of the cells making up the supporting structure in the bone marrow. The stromal cells have the characteristic of adhering to the bottom of plastic culture plates during culturing, and can differentiate into osteoblasts, chondrocytes, adipocytes, and even myoblasts. Stromal cells are required for the growth and differentiation of hematopoietic stem cells.

The production and number of stem cells will be greatly reduced as aging occurs, leading to various problems of aging, in which osteoporosis is the most common. The causes of osteoporosis include the loss of balance between bone formation and resorption. The osteoblastic cells derived from the osteoprogenitor cells are responsible for bone formation consisted of the formation of the bone matrix and skeletal mineralization. Osteoprogenitor cells come from the stromal cells in the bone marrow. Dexamethasone and ascorbic acid can promote the proliferation growth of osteoprogenitor cells, and enable the cells to differentiate into matured osteoblasts. During the differentiating process, different markers of osteoblasts are expressed: There is the deposition of collagenous matrix first, and after 10 to 14 days, alkaline phosphatase (ALP) is expressed. Alkaline phosphatase is widely used as a biochemical marker for identification of osteoblast activity, but its actual function is yet unknown, though currently it is believed that it participates in the skeletal mineralization process. After continuous culture to 21 days, the cells will secrete osteocalcein, and finally mineralize to form bone nodules.

It was unexpectedly found in this invention that the extract of the Dioscorea sp. or the further extracted fractions can be used to enhance the proliferation and differentiation of osteoprogenitor cells in the absence of any bone cell modulating agent, and thus, a composition comprising the active extract can be used in the treatment of the osteoporosis.

In the present invention, the extract is prepared from the root tuber part of Dioscorea sp. and is obtained using methanol as the extracting solution. The preparation process involves (a) extracting a tuber of Dioscorea sp. with an alcohol-based solvent in the presence of an acid, preferably in the presence of 1% acetic acid, in which the alcohol-based solvent is a methanol-based solvent, an ethanol-based solvent, or mixtures thereof.

In addition, the obtained extract may be further extracted on the basis of polarity, so as to obtain the pharmacologically active fractions. In one preferred embodiment of this invention, the extract is further subjected to partition chromatography comprising: (b) mixing a solvent mixture of ethyl acetate and water with the extract obtained from (a) so as to separate an ethyl acetate from a water extract existing in the water phase; (c) adding n-butanol solvent into the water phase to perform further extraction so as to separate a butanol extract from the remainder of water extract remaining in the water phase; and (d) adding 75% alcohol solvent into the water phase obtained from (c) to extract and further remove polysaccharide so as to obtain a purified water extract.

To confirm the biological activity of the components of Dioscorea sp., an analysis on the biological activity of the extract of Dioscorea tuber and the further extracted fractions were conducted on cells obtained from normal mice and a human patient suffering from glucocorticoid-induced osteoporosis.

From the experimental results shown in FIG. 1, it was unexpectedly found that the extract of Dioscorea sp. and the further extracted fractions enhance the proliferation of the osteoprogenitor cells without the aid of any bone cell modulating agent. Under the same concentrations, DHEA exhibits no effect of enhancing the proliferation of osteoprogenitor cells. In FIG. 2, the results showed that the extracts of Dioscorea sp. significantly increase the amount of the expressed alkaline phosphatase in normal cells, that is, the extracts prepared according to the present invention can stimulate the differentiation of osteoprogenitor cells into mature osteoblastic cells.

The inventor further confirmed the effect on abnormal bone marrow cells derived from a human patient suffering from glucocorticoid-induced osteoporosis. Glucocorticoids are essential therapies for a variety of inflammatory and autoimmune diseases. However, prolonged glucocorticoid use is one of the most common iatrogenic causes of osteoporosis. Glucocorticoids may increase bone loss through a variety of effects on osteobalsts, i.e., inhibition of the replication of the osteoblastic lineage, reduction of the genesis of new osteoblastic cells. From the results shown in FIG. 3, the inventor found that the active extract of the present invention increases the amount of the expressed alkaline phosphatase in such cells, and thus, the function of osteoblastic cells may be recovered by treating a patient suffering from glucocorticoid-induced osteoporosis with the active extract.

Moreover, in order to further confirm the effectiveness of the extract of Dioscorea sp. in treating osteoporosis in vivo, the inventor conducted experiments on normal mice and the mice that are ovariectomized to induce osteoporosis, which are orally administered with the extract of the present invention.

In FIGS. 4-5, the results demonstrate that the extract of Dioscorea sp., in vivo, increases the amount of the expressed alkaline phosphatase and the mineralization of the osteoblastic cells derived from normal mice and ovariectomized mice. Therefore, the extract of Dioscorea sp. not only regulates the proliferation and differentiation of osteoprogenitor cells but also controls bone formation and remodeling, and thus, the active extract can prevent and treat osteoporosis.

It was known that the proliferation and differentiation of bone marrow cells would be governed by certain factors, such as bone morphogenetic protein-2 (BMP-2), transforming growth factor-β (TGF-β), interlukin-4 (IL-4), epidermal growth factor (EGF), granulocyte-macrophage colony-stimulating factor (GM-CSF), etc. When the factor in the culture environment is changed, the stem cells differentiate into different cells in accordance with the specificity of such factors. For example, BMP-2, TGF-β, IL-4, and EGF are positively relevant to the proliferation and differentiation of the bone marrow stromal cells toward osteoblast lineage. In this study, the inventor conducted experiments to confirm the effects of the extract of Dioscorea sp. on gene expression of BMP-2, TGF-β, and IL-4, and the effects of the extract and the further extracted fractions of Dioscorea sp. on the proliferation and differentiation of bone marrow stem cells in the presence of EGF and GM-CSF.

In FIG. 6, the data demonstrated that the extract of Dioscorea sp. increases the gene expression of BMP-2, TGF-β, and IL-4, especially that of BMP-2 and TGF-β. Moreover, from the experimental results shown in FIG. 7 and Table 2, the inventor found that the extract of Dioscorea sp. stimulates the differentiation of the mouse bone marrow cells in the presence of EGF. The further extracted fraction of the extract, DioMPw, enhances the proliferation of mouse bone marrow cells.

As to GM-CSF, GM-CSF can act on a specific receptor complex present on hematopoietic progenitor cells to stimulate myelopoiesis, and thus, can promote the proliferation and differentiation of the hematopoietic progenitor cells in the bone marrow into monocytes, neutrophils, macrophages, etc.. Therefore, it is believed that GM-CSF has potential in therapy for restoring macrophages of a patient treated with chemotherapy. In this study, the inventor found that, in the presence of GM-CSF, the proliferation of the bone marrow cells was enhanced under the stimulation of the extract and the further extracted fractions of Dioscorea sp. (see Table 3). In addition, the results show that the differentiation of the stem cells was enhanced by the further extracted fractions of Dioscorea sp. Under the same conditions, DHEA exhibits the effect of enhancing cell differentiation, but cannot enhance cell proliferation. Therefore, this study suggests that the extract and the further extracted fractions of Dioscorea sp. prepared according to the present invention may assist GM-CSF in restoring the number of macrophages reduced by chemotherapy through the proliferation and differentiation of the bone marrow cells, and may be used as a chemotherapeutic adjuvant.

The inventor further confirmed the application of the extract of Dioscorea sp. on chemotherapy as a chemotherapeutic adjuvant in vivo. Cyclophosphamide (CY) is a drug used to treat a number of cancers; however, it destroys the bone marrow function, decreases the blood cells such as leukocytes, macrophages, and erythrocyte, and causes many other adverse side effects. In the present invention, cyclophosphamide is employed to cause leucopenia in mice to develop an animal model used to determine the function of the active extract of the present invention as a chemotherapeutic adjuvant. The obtained results showed that the active extract of the present invention prevented a decrease of leukocyte count and maintained the red blood cell count and hemoglobin content at normal level, and thus, accelerated recovery from leucopenia in CY-treated mice. Therefore, the active extract of the present invention can be used as a chemotherapeutic adjuvant to alleviate adverse side effects induced by an anti-cancer drug.

The experiments performed in accordance with the present invention clearly demonstrate that the extract of Dioscorea sp. and the further extracted fractions thereof enhance the proliferation and differentiation of the osteoprogenitor cells in the absence of any bone cell modulation agent, and thus, the present invention provides an application of Dioscorea sp. in the treatment of osteoporosis. Moreover, the extracts prepared according to the present invention increase and restore the number of the macrophages, leukocytes and erythrocytes which have been reduced by chemotherapy, and can thus be used as a chemotherapeutic adjuvant.

The following examples are provided to illustrate the present invention. The examples are not intended to limit the scope of the present invention and they should be so interpreted.

EXAMPLES OF THE INVENTION Preparatory Step 1 Preparation of a Methanol Extract of Dioscorea sp.

Four (4) kg peeled tubers of Dioscorea sp. were immersed in 1% (v/v) acetic acid solution overnight. The solid portion obtained was then frozen at −70° C. and lyophilized. The lyophilized portion was immersed in methanol in the presence of 1% acetic acid. After stirring and adjusting the concentration of methanol to 40% by volume, the mixture solution was allowed to stand overnight, and then separated by centrifugation. The obtained soluble fraction was lyophilized and is referred to as DioMs.

DioMs was further subjected to partition chromatography, comprising the steps of: using a solvent mixture of ethyl acetate and water (1:1) to extract DioMs so as to separate an ethyl acetate extract (referred as DioMPe) from a water extract existing in the water phase; adding n-butanol solvent into the water phase to perform further extraction so as to separate an butanol extract (referred as DioMPb) from the water extract remaining in the water phase; and adding 75% (v/v) alcohol solvent into the water phase to extract and further remove polysaccharide so as to obtain a purified water extract (referred as DioMPw).

Preparatory Step 2 Preparation of a Feed for Mice Containing a Methanol Extract of Dioscorea sp.

Purina Chow 5001, a commercially available mouse feed, was ground into powder. The lyophilized methanol extract of Dioscorea sp. was added in the ground feed in an amount to replace the same amount from the ground feed, to form a feed mixture. The feed mixture was uniformly mixed with distilled water, re-shaped by extrusion molding, baked for 2 min. in a microwave oven at proper power, and refrigerated at −70° C. after cooling to room temperature. After lyophilization, the feed mixture was formed into pellets very similar to the properties of the Purina Chow feed. The formed pellets are stored in −20° C. refrigerator. The pellets were warmed to room temperature on the day of feeding, and were sterilized by UV lamp irradiation on a sterile work table. Feed mixtures having different concentrations of methanol extract were prepared.

Preparatory Step 3 Isolation and Culture of Bone Marrow Cells

Under sterile conditions, SPF grade C3H/HeN mice were sacrificed and their femoral bones were injected with a liquid culture of DMEM/F12 to flush out the bone marrow cells. The cells were filtered through sterile No. 53 nylon mesh. The single cell suspension so obtained was mixed with DMEM/F12 culture medium containing N₂ to adjust to the proper concentration.

Preparatory Step 4 Preparation of Osteoprogenitor Cells from Mice

Under sterile conditions, femoral bones of the SPF grade of C3H/HeN mouse were obtained and injected with DMEM/F12. The bone marrow cells were flushed out and filtered through No. 53 sterile nylon mesh. The single cell suspension obtained was mixed with DMEM/F12 culture medium containing 15% FCS to adjust the concentration of the cells.

The cells were cultured in DMEM/F12 medium containing 15% FCS, 50 μg/ml ascorbic acid, 10 mM sodium β glycerophosphate and 10 nM dexamethasone in a T-flask for 6 days. The culture medium was renewed every 3 days. The cell concentration was 10⁶ cells/cm². On the 6^(th) day, the suspended cells and culture medium were drawn out. The adhering cell layer was washed with 1×PBS that had been warmed to room temperature, and then treated with 0.01% EDTA at 37° C. for 5 to 10 minutes. The EDTA was removed and the reaction was stopped in a culture medium containing FCS. The cells were all collected and centrifuged for 5 minutes at 1000 rpm.

Example 1 The Proliferative Response of Osteoprogenitor Cells of Mice Treated with the Methanol Extract and the Further Extracted Fractions of Dioscorea sp.

The cells obtained in preparatory step 4 were dispersed using a 22 G gauge needle and suspended in DMEM/F12 medium containing 15% FCS, 50 μg/ml ascorbic acid, 10 mM sodium β-glycerophosphate and 10 nM dexamethazone to form a concentration of 4.5×10⁴ cells/ml. 225 μl cell suspension was added into each well of a 96-well microplate. After 3 hours, to the cell suspension in each well was added 25 μl methanol extract, each of the further extracted fractions and DHEA and incubated for 72 hours. Then, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was performed. 1 mg/ml MTT solution was added in each well and reacted for 4 hours MTT lysis buffer (20% SDS-50% DMF) was added in each well in the amount of 150 μl/well and reacted for 16 hours, and the absorbance was measured at O.D. 570 nm for the resultant cell suspension in each well.

As shown in FIG. 1, under the stimulation of the methanol extract of Dioscorea sp., the proliferation of the osteoprogenitor cells was enhanced, in which the 0.01 and 0.1 μg/ml concentrations manifest significant enhancing effect. Under the same concentrations, DHEA exhibits no effect of enhancing the proliferation of osteoprogenitor cells. The extracted fractions, DioMPe and DioMPb, enhance cell proliferation at 10-400 μg/ml, wherein DioMPe exhibits an excellent effect.

Example 2 The Effect of the Methanol Extract and Different Extracted Fractions of Dioscorea sp. on the Differentiation of Matured Osteoblastic Cells of Mice Determined by Alkaline Phosphatase Activity (ALP) In Vitro

Osteoprogenitor cells collected in preparatory step 4 were incubated in a T-flask for 6 days. The cells were dispersed with 22 G gauge needle, and the cell concentration was adjusted to 5×10³ cell/cm². The cells were then incubated in 6-well plates, in which 4.5 ml of cell culture medium was added in each well, and 0.5 ml methanol extract and each of the extracted fractions were added the next day. After incubation for 14 days, alkaline phosphatase activity assay was conducted thereon, as described below.

Drawing out the culture medium, the cell layer was washed several times with PBS. 0.5% Triton X-100 in PBS was added into each well. The resultant suspension was subjected to a freezing and thawing process at a temperature of −70° C. and 37° C., respectively. The treatment was done twice so as to obtain a test sample. 50 μl of the test sample was transferred from each well to an ELISA plate. 50 μl AMP-substrate buffer (2-amino-2-methyl-1-propanol (AMP, 0.5M) in distilled water, pH 10; 2 mM magnesium chloride and 9 mM p-nitrophenyl phosphate) was then added into the ELISA plate so as to be reacted with the test sample at room temperature for 10-20 min. Immediately after the absorbance was measured at 410 nm wavelength using ELISA reader, the protein concentration of each well was measured quantitatively. The measure alkaline phosphatase activity is expressed in unit/μg.

As shown in FIG. 2, after 14 days of incubation of the bone marrow precursor cells, expression of alkaline phosphatase, which is the expressed marker specific to a matured osteoblast, was noted. The methanol extract of Dioscorea sp. and each of further extracted fractions of the methanol extract significantly increase the amount of the expressed alkaline phosphatase, in which the methanol extract at 0.1 μg/ml, DioMPb at 0.1 μg/ml, DioMPe at 0.01-0.1 μg/ml, and DioMPw at 0.1 μg/ml showed the strongest enhancement effect.

Example 3 The effects of the Methanol Extract Dioscorea sp. on Alkaline Phosphatase (ALP) Activity of Bone Marrow Cells Derived from a Patient Suffering from Glucocorticoid-Induced Osteoporosis

The patient's bone marrow cells obtained from the Taipei Veterans General Hospital were cultured in DMEM/F12 medium containing 15% FCS, 50 μg/ml ascorbic acid, 10 mM sodium β-glycerophosphate and 10 nM dexamethasone for 7 days. Alkaline phosphatase activity assay was conducted thereon.

As shown in FIG. 3, expression of alkaline phosphatase was noted. Compared with the control group and positive group (1 nM estrogen, which is the known treatment for osteoporosis), the methanol extract of Dioscorea sp. increased the amount of the expressed alkaline phosphatase, in which the methanol extract at 10 μg/ml showed the strongest enhancement effect.

Example 4 The Effects of Methanol Extract of Dioscorea sp. on Alkaline Phosphatase (ALP) Activity and on Mineralization of Bone Marrow Cells In Vivo

Different dosages (0, 40, 200, and 1000 mg/kg) of methanol extract were prepared for oral administration. After oral administration of different dosages of the methanol extract for 5 days, mice were sacrificed to obtain marrow cells thereof.

(1) Alkaline Phosphatase Activity Assay

The bone marrow cells of mice obtained were cultured in 96-well microplates at 2×10⁵ cells/well, in which 250 μl of α-MEM medium containing 15% FCS, 50 μg/ml ascorbic acid, 10 mM sodium β-glycerophosphate and 10 nM dexamethasone was added, and incubated in a 5% CO₂ incubator at 37° C. for 2 days. 125 μl/well of culture medium was drawn out and replaced by 125 μl/well of fresh medium containing 15% FCS, 50 μg/ml ascorbic acid, 10 mM sodium β-glycerophosphate, and 10 nM dexamethasone. After 4 days incubation, an alkaline phosphatase activity assay was conducted thereon.

As shown in FIG. 4A, expression of alkaline phosphatase was noted. In FIG. 4A, the methanol extract of Dioscorea sp. increases the amount of the expressed alkaline phosphatase, in which the methanol extract at 1000 mg/kg reaches up to 3 times enhancement as compared with the control group.

(2) Nodule Formation Assay

This assay is used to analyze the mineralization of the bone mass. The bone marrow cells obtained from the mice orally administered different dosages (0, 40, 200, and 1000 mg/kg) of methanol extract were seeded in 24-well plates at 1×10⁶ cells/well, cultured in α-MEM medium containing 15% FCS, 50 μg/ml ascorbic acid, 10 mM sodium β-glycerophosphate and 10 nM dexamethasone, and incubated in a 5% CO₂ incubator at 37° C. for 24 hrs. 500 μl/well of culture medium was drawn out and replaced by 500 μl/well of fresh medium containing 15% FCS, 50 μg/ml ascorbic acid, 10 mM sodium β-glycerophosphate and 10 nM dexamethasone. The cells were further incubated for 15 days to analyze the mineralization of the bone mass, and the culture medium renewed every 4 days. Nodule formation assay was conducted thereon, as described below.

Drawing out the culture medium, the cells were fixed by reacting them with 500 μl/well formalin for 30 minutes in a 5% CO₂ incubator at 37° C. After removing formalin and rinsing the cells with sterilized water three times, 200 μl/well of 2% Alizarine Red S solution, which reacts with calcium, was added into the wells and the cells were further incubated in a 5% CO₂ incubator at 37° C. for 10 minutes. Then, the Alizarine solution was removed and the cells were rinsed three times with absolute alcohol. The mineralized area of the bone mass was measured by Meta Image.

As shown in FIG. 4B, compared with the control group, the methanol extract of Dioscorea sp. promotes mineralization of the bone mass, in which the methanol extract at 1000 mg/kg dosage showed the strongest enhancement effect of up to 3.5 times.

Example 5 The Effect of the Methanol Extract of Dioscorea sp. on Alkaline Phosphatase (ALP) Activity and on Mineralization of Bone Marrow Cells in Ovariectomized Mice Model

Under sterile conditions, a group of SPF grade C57BL/6j mice were subjected to a surgical operation to remove their ovaries so as to induce the occurrence of osteoporosis and another group was merely operated on without removal of the ovary for use as a control group (referred to as pseudo operated mice).

Different dosages (0, 40, 200, and 1000 mg/kg) of methanol extract were prepared for oral administration. After being orally administered with different dosages of the methanol extract for 42 days, the mice were sacrificed to obtain bone marrow cells thereof.

(1) Alkaline Phosphate Activity Assay

The bone marrow cells obtained from the mice orally administered with different dosages (0, 40, 200, and 1000 mg/kg) of methanol extract and the pseudo operated mice were cultured in 96-well microplate at 2×10⁵ cells/well, in which 250 μl of α-MEM medium containing 15% FCS, 50 μg/ml ascorbic acid, 10 mM sodium β-glycerophosphate and 10 nM dexamethasone was added, and incubated in a 5% CO₂ incubator at 37° C. for 2 days. 125 μl/well of fresh medium containing 15% FCS, 50 μg/ml ascorbic acid, 10 mM sodium β-glycerophosphate and 10 nM dexamethasone was added. After 4 days incubation, an alkaline phosphatase activity assay was conducted thereon.

As shown in FIG. 5A, expression of alkaline phosphatase was noted. In FIG. 5A, the methanol extract of Dioscorea sp. is shown to increase the amount of the expressed alkaline phosphatase, in which the methanol extract at 1000 mg/kg showed the strongest enhancement effect.

(2) Nodule Formation Assay

The bone marrow cells obtained from the mice orally administered with different dosages (0, 40, 200, and 1000 mg/kg) of methanol extract were seeded in 24-well plates at 1×10⁶ cells/well, cultured in α-MEM medium containing 15% FCS, 50 μg/ml ascorbic acid, 10 mM sodium β-glycerophosphate and 10 nM dexamethasone, and incubated in a 5% CO₂ incubator at 37° C. for 24 hrs. 500 μl/well of culture medium was drawn out and replaced by 500 μl/well of fresh medium containing 15% FCS, 50 μg/ml ascorbic acid, 10 mM sodium β-glycerophosphate and 10 nM dexamethasone. The cells were further incubated for 15 days to analyze the mineralization of the bone mass, and the culture medium renewed every 4 days. A nodule formation assay was conducted thereon.

As shown in FIG. 5B, compared with the control group, the methanol extract of Dioscorea sp. promotes mineralization of the bone mass, in which the methanol extract at 1000 mg/kg showed the strongest enhancement effect.

Example 6 The Effect of the Methanol Extract Dioscorea sp. on Gene expression of Cytokines in the Bone Marrow Cells

Total RNA was extracted from he bone marrow cells obtained from Example 4 using an Ultraspec™ RNA isolation kit (Biotex laboratories Inc, U.S.A.). 5 μg total RNA and 2.5 μg oligo dT were heated at 70° C. for 10 minutes, cooled to room temperature for 10 minutes, then added with 4 μl 10 mM dNTP, 0.5 μl rRNasin, 1 μl (10 units) AMV (Avian Myeloblastosis virus) reverse transciptase and the buffer thereof, and the final reaction volume was 26.5 μl. The cDNA was obtained by reacting the previous reaction solution at 42° C. for 60 minutes and then at 90° C. for 5 minutes. 2.5 μl resultant cDNA was added with 0.5 μl 10 mM dNTP, 0.5 μl polymerase (2 units) and the buffer thereof, 1 μl of 10 μM targeted primers, and the final volume of the reaction mixture was 25 μl. PCR was performed for proper cycles, each cycle consisting of 45 seconds of denaturation at 94° C., 45 seconds of annealing at proper annealing temperature and 1 min of extension at 72° C. The reaction products were visualized by electrophoresis in 2% agarose gel. Sequences of the PCR primers are shown in Table 1. The experimental results are shown in FIG. 6.

As shown in FIG. 6, the gene expression of BMP-2, TGF-β, and IL-4 increased, especially BMP-2 and TGF-β.

TABLE 1 Sequences of the primers used in RT-PCR Cytokine Sequence (5′ to 3′) ^(a)Size (bp) IL-4 sense ATG GGT CTC AAC CCC CAG CTA GT  (SEQ ID NO: 1) antisense GCT CTT TAG GCT TTC CAG GAA 399 GTC  (SEQ ID NO: 2) TGF-β sense TGG ACC GCA ACA ACG CCA TCT ATG CCA TCT ATG AGA AAA CC (SEQ ID NO: 3) antisense TGG AGC TGA AGC AAT AGT TGG 525 TAT CCA GGG CT (SEQ ID NO: 4) BMP-2 Sense CAT CCA GCC GAC CCT TG (SEQ ID NO: 5) antisense CTC TCC CAC TGA CTT 505 GTG  (SEQ ID NO: 6) β-actin Sense GAC TAC CTC ATG AAG ATC CT (SEQ ID NO: 7) antisense CA CAT CTG CTG GAA GGT GG 510 (SEQ ID NO: 8) ^(a)The size of cytokine marker was determined by polymerase chain reaction (PCR) using the primers with reference to a 100 bp DNA ladder.

Example 7 Effects of Methanol Extract of Dioscorea sp. on Morphological Changes of Bone Marrow Cells of C3H Mice in the Presence of Epithelial Growth Factor (EGF)

1×10⁴ cells/well bone marrow cells of mice obtained in preparatory step 3 were seeded in a 96-well microplate containing DMEM/F12 culture medium with N₂ and 10 ng/ml EGF and incubated in a 5% CO₂ incubator at 37° C for 24 hrs. The extract and DHEA were added into different wells respectively. Wells containing pure culture medium into which no methanol extract and DHEA were added, and which were subjected to the same incubation procedure, were used as positive control. In addition, for use as positive control, the same procedure as that for control was repeated except that 50 ng/ml EGF was used. The proliferation responses were measured by a MTT assay. In accordance with the MTT assay, each of the wells was added with 1 mg/ml MTT solution and, after 4 hours of reaction, MTT lysis buffer (20% SDS-50% DMF) was added thereinto in an amount of 150 μl/well. The resultant mixture was allowed to be reacted for 16 hours. The absorbance was measured at O.D. 570 nm.

As shown in FIG. 7, in the event that the progenitor cells in bone marrow induced with EGF proliferate, the methanol extract of Dioscorea sp. was found to further stimulate the bone marrow progenitor cells to differentiate significantly. It can be noted that a more desirable optimum result was obtained when the concentration of the methanol extract used was at 10 μg/ml. It is further shown in Table 2 that when 10 μg/ml of DioMPw was used as stimulation, the cells exhibited significantly enhanced proliferative effect. Where that 100 μg/ml of DioMPw were used, the proliferation rate of the cell might reach up to 1.9 times that of the control as manifested in Table 2.

TABLE 2 Proliferation Morphologic Group Concentration Index^(a) Change^(b) Control 1.00 + DHEA 0.0001 μg/ml 0.99 + 0.001 μg/ml 0.64 + 0.01 μg/ml 0.65 + 0.1 μg/ml 0.67 ++ 1 μg/ml 0.70 ++ DioMPw 10 ng/ml 1.09 − 100 ng/ml 1.13 − 1 μg/ml 1.17 − 10 μg/ml 1.34* − 100 μg/ml 1.90* − ^(a)Data was analyzed by Student's t-test, and “*” means P < 0.05 ^(b)Morphologic change was observed by microscope.

Example 8 The Proliferation Response of Bone Marrow Cells of Mice Treated with Methanol Extract and the Further Extracted Fractions of Dioscorea sp. in the Presence of GM-CSF

1×10⁴ cells/well bone marrow cells of mice obtained in preparatory step 3 were seeded in each well of the 96-well microplate, cultured in DMEM/F 12 culture medium containing N₂, and 4 ng/ml mGM-CSF. Methanol extracts of Dioscorea sp. with different concentrations were respectively added into the resultant cultured cells in the different wells. The resultant methanol extract containing cultured cells in different wells were then incubated in a 5% CO₂ incubator at 37° C. for 14 days. The cells cultured in DMEM/F12 medium containing N₂ and 20 ng/ml mGM-CSF is used as positive control. A MTT assay was performed. In this respect, 1 mg/ml MTT solution was added in each well so as to react with the cultured cells therein for 4 hours. MTT lysis buffer (20% SDS-50% DMF) was added in a n amount of 150 μl/well. The resultant mixture was allowed to react for 16 hours. The absorbance was measured at O.D. 570 nm.

As shown in Table 3, under the stimulation of the methanol extract of Dioscorea sp. in concentrations ranging from 0.001 μg/ml to 1000 μg/ml, the fractions resulting from further extraction of the methanol extract are all found to have the ability to enhance cell proliferation. Among them, DioMPb and DioMPe were particularly found to have excellent effect on the enhancement of proliferation. In addition, the 20-week adult mouse bone marrow cells were found to be able to differentiate upon stimulation by the methanol extract of Dioscorea sp. at concentrations of 1 μg/ml-10 μg/ml. Among the extracted fractions of the methanol extract, which were extracted by a solvent mixture of water and ethyl acetate extracted fraction and the 75% alcohol extracted fraction resulting from further extracting the water extract with the 75% alcohol, are found to accelerate the differentiation of 20-week old adult mouse bone marrow cells. Under the same conditions, however, DHEA, in contrast, exhibits only the effect of enhancing cell proliferation. Therefore, the extracts of Dioscorea sp. which exhibit excellent effect on both the regeneration and differentiation of stem cells may assist GM-CSF in restoring the number of macrophages reduced by chemotherapy, and may be used as a chemotherapeutic adjuvant.

TABLE 3 Proliferation Morphologic Group Concentration Index^(a) Change^(b) Control 1.00 + DioMs 0.0001 μg/ml 1.08 + 0.001 μg/ml 1.19* + 0.01 μg/ml 1.68* + 0.1 μg/ml 1.95* + 1.0 μg/ml 1.78* ++ 10 μg/ml 1.82* +++ 100 μg/ml 1.49* + 1000 μg/ml 1.39* + DioMPe 0.01 μg/ml 0.98 + 0.1 μg/ml 1.11 ++ 1 μg/ml 1.35* ++ 10 μg/ml 2.64* +++ 100 μg/ml 0.83  −^(c) 300 μg/ml 0.97 − DioMPb 0.01 μg/ml 1.07 + 0.1 μg/ml 1.23 + 1 μg/ml 1.34 + 10 μg/ml 1.41 + 100 μg/ml 1.90* + 300 μg/ml 2.02* + DioMPw 0.0001 μg/ml 1.06 + 0.001 μg/ml 1.08 + 0.01 μg/ml 1.12 ++ 0.1 μg/ml 1.18 ++ 1.0 μg/ml 1.31* +++ 10 μg/ml 1.56* + DHEA 0.0001 μg/ml 0.99 + 0.001 μg/ml 1.15 + 0.01 μg/ml 1.04 + 0.1 μg/ml 1.13 + 1 μg/ml 1.11 +++ 10 μg/ml 1.19* + ^(a)Data was analyzed by Student's t-test, and means P < 0.05 ^(b)Morphologic change was observed by microscope. ^(c)Bone marrow cells were found dead under high concentration of DioMPe.

Example 9 The Effect of the Methanol Extract on the Number of Leukocyte and Red Blood Cells and Hemoglobin Content in Peripheral Blood of Leukopenia Mice Induced by Cyclophosphamide

Different dosages (0, 20, 100, and 500 mg/kg) of methanol extract were prepared for oral administration. The mice were intraperitoneally injected with 200 and 100 mg/kg of cyclcophosphamide (CY) on day 0 and day 5 to cause leucopenia, and blood was drawn periodically to cause an anemia condition. The mice were orally administered different dosages of the methanol extract on day 1 until the mice were sacrificed. The peripheral blood collected from the retro-orbital sinus was sampled on days 0, 4, 8, and 12.

The blood (0.1 ml) obtained on days 0, 4, 8, and 12 was added with 25 μl EDTA solution (72 mg/ml) to prevent blood coagulation, and diluted 10× or 20× with Turk's solution (2% acetic acid with 0.01% crystal violet). The numbers of leukocytes were counted by microscope.

To the blood (0.1 ml) obtained on day 8 was added 25 μl EDTA solution (72 mg/ml). to prevent blood coagulation, and diluted 2000× with saline. The number of erythrocytes was counted. Hemoglobin (Hbg) content was determined as described by Worthington R. E. et al., Experimental Hematology, 15:85-92, 1987.

From the results shown in FIGS. 8-10, it is noted that the active extract of the present invention mitigates reduction of leukocyte number in peripheral blood and accelerates recovery of leukocytes, and maintains the red blood cells and Hbg content at normal levels.

Example 10 Characterization of Dioscorea Species in a Randomly Amplified Polymorphic DNA (RAPD) Analysis DNA Extraction

The Dioscorea species from which the extracts were produced and administered as described above, Dioscorea alata L. cv. Phyto, was harvested from the Yang-Ming Mountain in Taiwan. The Dioscorea alata L. cv. Phyto (shown in duplicate as Sample No. 100 or 102) was characterized along with a test panel of 13 known Dioscorea species, including Dioscorea alata L. cv. (cultivated variety) Tainung No. 1 (Sample No. 1), Dioscorea esculenta (Sample No. 3), Dioscorea bulbifera (Sample No. 4), Dioscorea alata L. cv. 8702 (Sample No. 5), Dioscorea alata L. cv. Sanzhi A (Sample No. 6), Dioscorea alata L. cv. Sanzhi B (Sample No. 7), Dioscorea alata L. cv. Dayeshoufeng (Sample No. 9), Dioscorea alata L. cv. Tainung No. 2 (Sample No. 10), Dioscorea alata L. cv. Jifa (Sample No. 67), Dioscorea alata L. cv. Zhanger No. 2 (Sample No. 64), Dioscorea alata L. cv. Dashan No. 3 (Sample No. 13), Dioscorea alata L. cv. Dashan No. 2 (Sample No. 12) and Dioscorea alata L. cv. Taidong (Sample No. 11), all of which were grown in Taiwan.

0.2 g of fresh leaf of each Dioscorea sample was collected and ground in a mortar mixed with liquid nitrogen. The ground tissue was mixed with 900 μl of 2% CTAB extraction buffer (containing 1.4 M NaCl, 100 mM Tris-HCl at pH 8.0, 20 mM EDTA and 0.2% β-mecaptoethanol) in a 1.5 ml centrifuge tube, followed by incubating in a 65° C. water bath for 30 minutes. The sample was then centrifuged, and the supernatant was transferred to a clean tube added with 600 μl of chloroform/isoamylalcohol (24:1) and vortexed until the sample was in an emulsified state. The sample was further centrifuged, and the supernatant was transferred to a clean tube and mixed with 40 μl of 10% CTAB (containing 0.7M NaCl) and 400 μl of chloroform/isoamyl alcohol (24:1). The sample was centrifuged again, and the supernant (400 μl) was transferred in a clean tube and mixed with 400 μl of CTAB precipitation buffer and left on ice for about 15-20 minutes to precipitate DNA. The DNA sample was rinsed with 400 μl of high-salt TE (10 mM Tris-HCl, pH 8.0; 1 mM EDTA; and 1M NaCl) and 800 μl of 95% alcohol. The DNA sample was centrifuged, and the pellet was further rinsed with 400 μl of 75% alcohol before re-suspending the DNA pellet in distilled and deionized (dd)H₂O and stored at −20° C.

RAPD Reaction

A random RAPD primer of SEQ ID NO:9, in this case OPA-18 (AGGTGACCGT) (Operon Technologies, USA) was used to amplify genomic DNA of the Dioscorea species in the RAPD analysis. Polymerase Chain Reaction (PCR) was carried out in a 25 μl volume containing 10× buffer, 2.5 mM of each dNTP (dATP, dCTP, dGTP, and dTTP), 2.0 μM of primer (Operon), 5 units of Taq DNA polymerase (TaKaRa Biomedicals), and 5 ng template DNA. Samples were subjected to 41 cycles consisting of denaturation for 1 min at 94° C., annealing for 1 min at 36° C., extension for 2 min at 72° C., and one final extension cycle at 72° C. for 10 minutes. After completion of the PCR, 10 μL of reaction mixture was loaded into a 2% agarose gel, containing 0.5 μg/mL ethidium bromide for electrophoresis.

Data Analysis

In the gel electrophoresis, both first lane (on the far left) and last lane (on the far right) of the gel were loaded with DNA molecular weight marker (M), such as ΦX174 DNA/HaeIII marker (Promega Co., USA) to provide reference bands of different sizes, such as 500 bp, 1000 bp, 1500 bp, 2000 bp, 2500 bp, 3000 bp, 3500 bp and 4000 bp, followed by loading the PCR sample of each Dioscorea species in each lane. The profile of amplified DNA products from each sample was visualized by fluorescent developer and photographic images were captured using an image acquiring software, AlphaImager 1220. Since each Dioscorea species from the test panel produced its own DNA bands in the RAPD fingerprint, the RAPD fingerprint of the Dioscorea species of the invention was determined to distinguish from other Dioscorea species. As shown in FIG. 11, there are 14 DNA bands ranging from 428 bp, 452 bp, 537 bp, 602 bp, 723 bp, 817 bp, 934 bp, 1140 bp, 1242 bp, 1478 bp, 1641 bp, 1904 bp, 2151 bp and 2918 bp for characterizing the Dioscorea alata L. cv. Phyto (shown in duplicate as samples No. 100 or 102) when genomic DNA of the Dioscorea species is amplified with the OPA-18 primer of SEQ ID NO:9.

A cluster analysis or pair analysis was also carried out using Gel-Compar software to calculate a similarity index between two Dioscorea species. Parameters subjected to the analysis were from RAPD fingerprints. Next, with the unweighted pair-grouping mean arithmetical analysis (UPGMA), the similarity index (F) was calculated in a cluster analysis with the following equation: F=2n _(xy) /n _(x) +n _(y) wherein n_(xy) is the number of common DNA bands in Dioscorea species x and y, and n_(x) and n_(y) are the total DNA bands in Dioscorea species x and y respectively (Nei, M. and W. H. Li. 1979, Mathematical Model for studying genetic variation in terms of restriction endonucleases, Proc. Natl. Acad. Soc. U.S.A. 76: 5269-5273).

Referring to FIG. 12, a phylogenetic tree was constructed based on the similarity index between 14 Dioscorea species in the test panel. As illustrated in FIG. 12, the unknown Dioscorea species has a similarity index of about 88.9% with Dioscorea alata L. cv. Sanzhi A or Dioscorea alata L. cv. Zhanger No. 2. Furthermore, the Dioscorea species has a similarity index of about 37.5% with Dioscorea bulbifera or Dioscorea esculenta. Moreover, the Dioscorea alata L. cv. Phyto has a similarity index of more than 75.5% with Dioscorea Dioscorea alata L. cv. Tainung No. 1, Dioscorea alata L. cv. 8702, Dioscorea alata L. cv. Sanzhi B, Dioscorea alata L. cv. Dayeshoufeng, Dioscorea alata L. cv. Tainung No. 2, Dioscorea alata L. cv. Dashan No. 3 or Dioscorea alata L. cv. Dashan No. 2.

Based on the cluster analysis or pair analysis results, it was understood that Dioscorea alata L. cv. Phyto is different from known species, but more similar to Dioscorea alata sub-species. The Dioscorea alata L. cv. Phyto is also known as Dioscorea alata (No. YMM-PH3), which is the scientific name given by the Research Center for Drug Discovery at the National Yang Ming University, Taipei, Taiwan, R.O.C.

Each and every patent, patent application and publication referred to herein is hereby incorporated by reference herein in its entirety

It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as defined by the appended claims. 

I claim:
 1. A method for treating osteoporosis in a subject in need of such treatment, comprising administering orally to the subject an effective amount of an extract product of Dioscorea alata, wherein the extract is capable of promoting proliferation and differentiation of bone marrow cells in the subject, wherein the extract product is prepared by a process comprising: (a) extracting a tuber of Dioscorea alata with an alcohol-based solvent in the presence of 1% acetic acid to obtain a resultant product; (b) subjecting the resultant product in (a) to centrifugation resulting in a soluble fraction and insoluble fraction; and (c) collecting said soluble fraction, and removing solvent from the soluble fraction to obtain said extract product.
 2. The method according to claim 1, wherein the alcohol-based solvent used in (a) of the process is a methanol-based solvent, an ethanol-based solvent, or a mixture thereof.
 3. The method according to claim 1, wherein the alcohol based solvent in (a) is a 40% methanol solvent having the 1% acetic acid.
 4. The method according to claim 1, wherein prior to (a) of the process, the tuber of Dioscorea alata is subjected to a preliminary treatment including the steps of: (i) immersing the tuber of Dioscorea alata in a 1% acetic acid solution; (ii) freezing the acetic acid-treated tuber of Dioscorea alata; and (iii) lyophilizing the frozen tuber of Dioscorea alata.
 5. The method according to claim 1, wherein Dioscorea alata is Dioscorea alata L. cv. Phyto, characterized by a randomly amplified polymorphic DNA (RAPD) fingerprint comprising 14 DNA bands ranging from 428 bp, 452 bp, 537 bp, 602 bp, 723 bp, 817 bp, 934 bp, 1140 bp, 1242 bp, 1478 bp, 1641 bp, 1904 bp, 2151 bp and 2918 bp, respectively, when genomic DNA of the Dioscorea species is amplified with a primer of SEQ ID NO:9. 